The latest model, Roku 3, sells for about $100 and works only on HD televisions. Other models start at about $50 and work on almost any TV.

Roku 3 allows viewers to stream 1080p videos from more than 700 channels, including Netflix, Amazon Instant Video, Hulu, PBS and Vudu, an on-demand movie and TV streaming service. Roku also boasts that it offers the biggest selection of live sports streaming packages, from MLB.TV and NBA League Pass Broadband to NHL GameCenter and professional soccer.

To connect the device to your television set, you use an HDMI (high-definition multimedia interface) cable, which isn’t included with the device. Next, you plug it into a power source with an adapter, which is included, and add it to a wireless network or ethernet so you can start streaming..

Roku 3 comes with a remote control, but you also may use your iPhone or Android smartphone to scroll through channels or start a show.

Apple TV

The third-generation Apple TV became available in March 2012 and supports 1080p video. Another update is rumored to be on the way soon.

A little black box that weighs less than 10 ounces, Apple TV costs about $100 and can be hooked up to your television with an HDMI cable, sold separately. The device comes with a remote, and also may be manipulated from a mobile app. The Air Play feature lets you stream content wirelessly from your iPod, iPad, iPhone or computer to your TV.

You’ll need the latest version of iTunes.

Apple TV is a good option for people with Apple devices who use a lot of iTunes content, but the device also can stream TV shows and movies from YouTube and Vimeo or Netflix.

Live professional baseball, basketball and hockey are available for streaming by subscription from MLB.TV, NBA League Pass and NHL GameCenter.

Western Digital WD TV Play

Priced at about $70, the Western Digital WD TV Play is not only one of the cheaper set-top boxes, but it also is the most highly rated by Consumer Reports.

The device streams videos from Netflix, Hulu Plus, Vudu, Cinema Now and Pandora, as well as Spotify and YouTube, both of which aren’t available on Roku. But it doesn’t offer Amazon Prime or live sports apps, a drawback for some viewers.

The Western Digital WD TV Play comes with a remote control and a USB port to upload movies and photos directly from your digital camera or memory stick.

Google Chromecast

Google Inc. introduced its Chromecast dongle in July. The 2-inch gadget plugs into HDMI connections. Those slots can be found, typically out of sight, on most high-def TVs sold in the past five years.

With relative ease, the Chromecast puts the TV screen to work displaying anything that appears on your Chrome Web browser. It also works with a limited number of applications, notably Netflix and YouTube.

The Chromecast doesn’t come with a remote, so customers must use their smartphones, tablets or computers as remotes.

Users can fire up a movie or YouTube video on the TV and still use their mobile devices to check email or perform other functions that aren’t showing up on the TV – even as they control the volume, pause, play and rewind functions with the devices in their laps. The Chromecast and the mobile device just need to be operating on the same Wi-Fi network.

Perhaps the biggest allure is the price. The Chromecast costs just $35, challenging Roku and other gadget makers that simplify the job of putting Web content on the living room TV.

Aereo

Aereo is a subscriber service that lets you watch and record free-over-the-air television channels on the Internet using compatible devices such as Apple TV, Roku, desktop browsers and mobile devices.

Pay-TV channels such as HBO, AMC and ESPN aren’t available through Aereo.

For a basic monthly membership of $8 you get 20 hours of DVR space to record your shows. An upgrade for $12 gives you 60 hours of storage plus the ability to record two shows at once or watch one channel live while recording another.

Customers in select cities may sign up by visiting https://aereo.com.

Netflix

Netflix charges customers $8 per month to stream unlimited movies and TV, including some popular Netflix-only shows such as “Orange Is the New Black” and “House of Cards.”

Vudu

Unlike Netflix’s subscription service, Vudu’s lets you pay per view. Movies in HD – including recent releases -- are available to rent online for $2 for two nights. You also may buy TV seasons to download and own.

Hulu, Hulu Plus

Hulu’s free service lets viewers stream popular TV series and movies with some commercials on their computers for free, usually after they air. Sometimes the delay is just a day, but it can be as long as a week or even an entire season. For $8 a month, Hulu Plus customers get access to archives of past seasons, an extensive library of movies and the ability to stream videos to their mobile devices and television sets.

Amazon Instant Video

Amazon Prime membership costs $79 a year and includes free two-day shipping as well as free streaming of selected TV series and movies. The videos can be downloaded to your Kindle Fire device or cloud to store and watch later. However, many popular shows aren’t included in the Prime membership, and must be bought a la carte, like iTunes. The selection is limited and Amazon still isn’t available on many box-top devices or TVs.

Cinema Now

Best Buy’s Cinema Now lets you buy or rent TV shows and movies and store them in a cloud or watch them immediately on a tablet, mobile device, game console, TV or Blu-ray player.